Method for transmitting emergency call messages in a radio communications system

ABSTRACT

At least one of voice and data information is transmitted in connection mode via a radio interface in first radio zones. In second radio zones, voice or data information is transmitted exclusively in packet mode via a radio interface. When an emergency call is issued by a subscriber station from one of the first radio zones, a voice and/or data connection is established between the subscriber station and an emergency control center. When an emergency call is issued by a subscriber station from one of the second radio zones, at least one piece of emergency information which identifies the second radio zone is transmitted to an emergency control center.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and hereby claims priority to GermanApplication No. 100 37 740.8 filed on Aug. 2, 2000, the contents ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Until now, it has been possible to send emergency call messages onlyfrom radio cells in which connection-oriented services are available. Adocument (Tdoc SMG2 EDGE 298/99) which was submitted at the ETSI SMG2EDGE Workshop from Aug. 24 to 27, 1999 in Paris relates to the sendingof emergency call messages from areas of a radio communications systemin which only packet-oriented services or only connection-orientedservices are available in some radio cells while, in contrast,packet-oriented and connection-oriented services are available in otherradio cells. This document proposes that, when an emergency call messageis to be sent from a subscriber station in a radio cell with exclusivelypacket-oriented services, a handover process be initiated for thissubscriber station, with the aim of associating the relevant subscriberstation with a radio cell with connection-oriented services.

In order to speed up the handover process, Section 11.2.19, page 160requires that the subscriber station be informed via a signaling channelthat connection-oriented services are not available in the originallyselected radio cell. A message such as this is advantageous whenever,for example, connection-oriented services are available in one of theadjacent radio cells and this radio cell is selected by the handoverprocess. However, if connection-oriented services are not available inany of the feasible radio cells, a procedure such as this runs intoconsiderable problems.

SUMMARY OF THE INVENTION

The present invention is based on the object of specifying a method fortransmitting emergency call messages which originate from a subscriberstation in a radio cell in which no connection-oriented service isavailable.

One major aspect of the method according to the invention is that, inthe case of an emergency call originating from a subscriber station in aradio cell in which at least one of speech and data information aretransmitted exclusively in a packet-oriented manner via a radiointerface, an emergency call center is signaled that an attempt has beenmade to set up a connection to an emergency call center in a radio cellin which no connection-oriented services are available. The aim in thesignaling of the emergency call is to detect information that is asvalid as possible about, for example, the location or the identity of auser who is sending the emergency call, and to transmit this to theemergency call center. A minimum requirement in this sense is thus thetransmission of information which identifies the radio cell of the userwho is sending the emergency call. According to one preferreddevelopment of the method according to the invention, a unidirectionalspeech information interchange also takes place, from the relevantsubscriber station to the emergency call center.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention willbecome more apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a block diagram of a conventional radio communications system,in which only connection-oriented services are available, having anemergency call center, and

FIG. 2 is a block diagram of a radio communications system in whichconnection-oriented and packet-oriented services are available, havingan emergency call center.

FIG. 3 is a flowchart of a method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

The structure of the radio communications system which is illustrated inFIG. 1 corresponds to that of a known GSM mobile radio network which hasa large number of mobile switching centers MSC for connection-orientedservices, which are networked to one another and allow access to alandline network PSTN or to some other radio communications networkPLMN. The mobile switching centers MSC may be connected to an emergencycall center EC either directly or indirectly via the landline networkPSTN. A connection is also possible between the mobile switching centersMSC and the emergency call center EC via some other radio communicationsnetwork PLMN.

Furthermore, the mobile switching centers MSC are connected to at leastone base station controller BSC. Each base station controller BSC allowsa connection to be set up to at least one base transceiver station BTS.Base station controllers BSC and associated base transceiver stationsBTS are combined to form a base station subsystem BSS. A basetransceiver station BTS may set up a unidirectional or bidirectionalspeech and/or data connection to a subscriber station TS via a radiointerface. A large number of radio channels Ch1 to CHn are available atthe radio interface for connection-oriented transmission of speechand/or data information within a radio cell C.

If an emergency caller HC sends an emergency call via a subscriberstation TS, then the process of setting up the connection between thesubscriber station TS of the emergency caller HC and the emergency callcenter EC is subject to numerous simplifications. These simplificationsinclude, for example, higher-prioritized handling of the process ofsetting up the connection, dispensing with any check of informationwhich is stored on a SIM card (Subscriber Identification Module) forgranting of network or service access authorizations, or dispensing withterminal-identification-dependent blocking of access authorizations.

In the radio communications system illustrated in FIG. 2,packet-oriented services are also available, in addition toconnection-oriented services. Packet-oriented services are usedpredominantly for the transmission of data information, whileconnection-oriented services are intended primarily for the transmissionof speech information.

In GSM mobile radio systems by way of example, packet-oriented servicesare provided by GPRS (General Packet Radio Services). GPRS allows atheoretical data transmission rate of 182 kb/s. In practice, datatransmission rates of 150 to 170 kb/s can be expected. In addition tothe components which have already been illustrated in FIG. 1, the radiocommunications system which is illustrated in FIG. 2 has a number ofadditional components especially for packet-oriented services. Forexample, for packet-oriented services, the base station controller BSCis coupled to a packet data network PDN via a router SGSN (Serving GPRSSupport Node) and a gateway GGSN (Gateway GPRS Support Node). The routerSGSN is also coupled to a mobile switching center MSC via a furthergateway GMSC.

There are a number of options, as shown in FIG. 2, for coupling anemergency call center EC to the radio communications system. Firstly, inthe radio communications system illustrated in FIG. 1, the mobileswitching centers MSC may be connected to an emergency call center ECeither directly or indirectly via the landline network PSTN. By analogywith FIG. 1, a connection is also possible between the mobile switchingcenters MSC and the emergency call center EC via some other radiocommunications network PLMN. In addition to this, it is possible tocouple the emergency call center EC directly to the packet data networkPDN. In this case, the emergency call center EC could also be equippedwith packet-data-processing terminals, which allow data packets to beconverted to analog speech information.

Depending on the requirements resulting from the network plan, scenariosare possible in which only connection-oriented or only packet-orientedservices are available in some radio cells, and both types of serviceare available in other radio cells. It is thus possible for onlypacket-oriented services to be available in a chosen radio cell. FIG. 2considers a scenario in which speech and/or data information can betransmitted 10 (FIG. 3) on a connection-oriented or packet-orientedbasis via the radio interface in a first radio cell C1, while onlypacket-oriented services are available 20 in a second radio cell C2.

On the basis of the method according to the invention, when an emergencycall occurs which is sent from a subscriber station TS1 of a firstemergency caller HC1, a speech and/or data connection is set up 12 tothe emergency call center EC via one or more of the radio channels CDCH1to CDCHn, which are available in the first radio cell C1, forconnection-oriented services. In the case of an emergency call which issent from a subscriber station TS2 of a second emergency caller HC2 inthe second radio cell C2, at least one emergency call information itemwhich identifies the radio cell C2 is transmitted 22 to the emergencycall center EC.

The emergency call information is, for example, transmitted at least insections in a packet-oriented manner via radio channels PDCH1 to PDCHn,the base transceiver station BTS, the base station controller BSC, therouter SGSN, the gateway GMSC and the mobile switching center MSC to theemergency call center EC.

Data which has until that point been transmitted in a packet-orientedmanner is converted at the gateway GMSC to data based on aconnection-oriented transmission protocol. As an alternative to thesketched procedure, it is possible to transmit the emergency callinformation via a further gateway GGSN and the packet data network PDNto the emergency call center EC. In this case, notransmission-protocol-dependent conversion is required for the data.

The emergency call information may also optionally identify the physicalposition of the subscriber station TS2 of an emergency caller HC2.Corresponding position information may be generated either at thenetwork end from the knowledge of the microcell, nanocell or picocell ina radio network in which the emergency caller HC2 is currently located,or at the subscriber station end if, for example, a subscriber stationTS2 is equipped with a GPS transmitter and receiver, and this positioninformation can be added 24 to the emergency call information. If theemergency call information is also used to transmit to the emergencycall center EC details relating to the identification of a subscriberstation TS2, by which the emergency caller HC2 can also be indirectlyidentified, then these details can be used to access data recordingdevices which, for example, contain information relating to adebilitation pattern, profile or medication incompatibilities of apatient, to simplify the preparations for medical assistance measures,or, in particular, also to speed them up.

In addition to the transmission of emergency call information, it isalso possible to receive analog speech information at the subscriberstation TS1, TS2 of an emergency caller HC2, for this information to beconverted to digital packets, and to be transmitted to the emergencycall center EC. The analog speech information may in this case betransmitted 26, for example, via a VoIP connection (Voice over InternetProtocol) or by a tone file (wave file). A speech informationinterchange such as this may be carried out both unidirectionally fromthe subscriber station TS2 of an emergency caller HC1, HC2 to theemergency call center EC and bidirectionally between the emergency callcenter EC and the subscriber station TS2. In the latter case, analoguespeech information which is received at the emergency call center EC canbe converted to digital data packets and can be transmitted 28 in apacket-data-oriented manner to the subscriber station TS1, TS2 forreproduction.

In order to signal to an emergency caller HC2 who is sending anemergency call from the second radio cell C2 by his subscriber stationTS2 that, for example, only unidirectional emergency call connections oremergency call connections with restricted speech quality are possiblefrom the second radio cell C2, the emergency caller HC2 is informed fromthe network end about a corresponding signaling channel in the sense ofuser guidance that only packet-oriented services are available in thechosen radio cell. Furthermore, emergency call data packets which haveemergency call information that identifies the second radio cell HC2and/or which contain speech information received at the subscriberstation end are assigned an increased transmission priority.

The functionality and the structure of the radio communications systemillustrated in FIG. 2 can in principle also be transferred to otherradio communications systems in which the invention may be used, inparticular for subscriber access networks with wire-free subscriberaccess. The use of the method according to the invention is thus notrestricted to the exemplary embodiments described here.

The invention has been described in detail with particular reference topreferred embodiments thereof and examples, but it will be understoodthat variations and modifications can be effected within the spirit andscope of the invention.

1. A method for transmitting emergency call messages in a radiocommunications system, comprising: transmitting at least one of speechand data information on a connection-oriented basis via a first radiointerface in first radio cells; transmitting at least one of speech anddata information exclusively in a packet-oriented manner via a secondradio interface in second radio cells; setting up a connection betweenthe subscriber station and an emergency call center for at least one ofspeech and data in response to a first emergency call originating from afirst subscriber station in one of the first radio cells; andtransmitting emergency call information to the emergency call center, inresponse to a second emergency call originating from a second subscriberstation in one of the second radio cells, the emergency call informationidentifying the one of the second radio cells.
 2. The method as claimedin claim 1, wherein the emergency call information is transmitted atleast in sections in a packet-oriented manner to the emergency callcenter.
 3. The method as claimed in claim 2, wherein the emergency callinformation is transmitted to the emergency call center via a networkfor packet-oriented data transmission.
 4. The method as claimed in claim3, wherein the emergency call information identifies a position of thesecond subscriber station from which the emergency call is signaledwithin the one of the second radio cells.
 5. The method as claimed inclaim 4, wherein, at a network end, an information item relating to aposition of the second subscriber station from which the secondemergency call is being signaled is generated and is added to theemergency call information.
 6. The method as claimed in claim 4,wherein, at a subscriber station end, an information item relating to aposition of the second subscriber station from which the secondemergency call is being signaled is generated and is added to theemergency call information.
 7. The method as claimed in claim 6, whereinthe emergency call information contains details for identification ofthe second subscriber station from which the second emergency call isbeing signaled.
 8. The method as claimed in claim 7, further comprisingtransmitting to the emergency call center, in response to the secondemergency call originating from the second subscriber station, firstspeech information detected at a transmitter end, in apacket-data-oriented manner via the second radio interface and then viaan interface for conversion of data based on a packet-oriented protocolto data based on a connection-oriented protocol.
 9. The method asclaimed in claim 8, further comprising transmitting second speechinformation, detected at a receiver end, from the emergency call centerto an interface for conversion of data based on a connection-orientedprotocol to data based on a packet-oriented protocol, and then via aradio interface to the second subscriber station.
 10. The method asclaimed in claim 7, wherein, for the second emergency call originatingfrom the second subscriber station, first speech information detected ata transmitter end is converted to a sequence of data packets, and sentvia a unidirectional connection to the emergency call center.
 11. Themethod as claimed in claim 10, wherein, for the second emergency calloriginating from the second subscriber station, the second subscriberstation is signaled that only packet-oriented services are available.12. The method as claimed in claim 11, wherein emergency call datapackets containing emergency call information at least one ofidentifying the one of the second radio cells and containing speechinformation detected at a second subscriber station end are assigned anincreased transmission priority.